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Neisseria. General Characteristics of Neisseria spp. Aerobic Gram-negative cocci often arranged in pairs ( diplococci ) with adjacent sides flattened (like coffe beans) Oxidase positive Most catalase positive Nonmotile Acid from oxidation of carbohydrates, not from fermentation.

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General Characteristics of Neisseria spp.

  • Aerobic

  • Gram-negative cocci often arranged in pairs (diplococci) with adjacent sides flattened (like coffe beans)

  • Oxidase positive

  • Most catalase positive

  • Nonmotile

  • Acid from oxidation of carbohydrates, not from fermentation


Important Human Pathogens

Neisseria gonorrhoeae

Neisseria meningitidis

Other species normally colonize mucosal surfaces of oropharynx and nasopharynx and occasionally anogenital mucosal membranes


Neisseria Associated Diseases

(ophthalmia neonatorum)



Neisseria gonorrhoeae spp.

(gonococcus)


General Overview of Neisseria gonorrhoeae spp.

  • Readily transmitted by sexual contact

  • Gram-negative diplococci flattened along the adjoining side

  • Fastidious, capnophilic and susceptible to cool temperatures, drying and fatty acids

    • Requires complex media pre-warmed to 35-37C

    • Soluble starch added to neutralize fatty acid toxicity

    • Grow best in moist atmosphere supplemented with CO2

  • Produce acid from glucose, but not from other sugars



Epidemiology of Gonorrhea spp.

  • Seriously underreported sexually-transmitted disease

    • 350,000 reported cases in USA in 1998

    • Down from 700,00 cases in 1990

  • Found only in humans with strikingly different epidemiological presentations for females and males

  • Asymptomatic carriage is major reservoir

  • Transmission primarily by sexual contact

  • Lack of protective immunity and therefore reinfection, partly due to antigenic diversity of strains

  • Higher risk of disseminated disease in patients with late complement deficiencies



Differences Between Men & Women with Gonorrhea spp.

  • IN MEN:

  • Urethritis; Epididymitis

  • Most infections among men are acute and symptomatic with purulent discharge & dysuria (painful urination) after 2-5 day incubation period

  • Male host seeks treatment early preventing serious sequelae, but not soon enough to prevent transmission to other sex partners

  • The two bacterial agents primarily responsible for urethritis among men are N. gonorrhoeae and Chlamydia trachomatis


Differences Between Men & Women with Gonorrhea spp.(cont.)

  • IN WOMEN:

  • Cervicitis; Vaginitis; Pelvic Inflammatory Disease(PID);Disseminated Gonococcal Infection(DGI)

  • Women often asymptomatic or have atypical indications (subtle, unrecognized S/S); Often untreated until PID complications develop

  • Pelvic Inflammatory Disease (PID)

    • May also be asymptomatic, but difficult diagnosis accounts for many false negatives

    • Can cause scarring of fallopian tubes leading to infertility or ectopic pregnancy


Differences Between Men & Women with Gonorrhea spp.(cont.)

IN WOMEN (cont.):

  • Disseminated Gonococcal Infection (DGI):

    • Result of gonococcal bacteremia

    • Often skin lesions

    • Petechiae (small, purplish, hemorrhagic spots)

    • Pustules on extremities

    • Arthralgias (pain in joints)

    • Tenosynovitis (inflammation of tendon sheath)

    • Septic arthritis

    • Occasional complications: Hepatitis; Rarely endocarditis or meningitis


Gonorrhea spp.


Pathogenesis of Neisseria gonorrhoeae spp.

  • Fimbriated cells attach to intact mucus membrane epithelium

  • Capacity to invade intact mucus membranes or skin with abrasions

    • Adherence to mucosal epithelium

    • Penetration into and multiplication before passing through mucosal epithelial cells

    • Establish infection in the sub-epithelial layer

  • Most common sites of inoculation:

    • Cervix (cervicitis) or vagina in the female

    • Urethra (urethritis) or penis in the male


Gonococcal Virulence Factors spp.

  • Antiphagocytic capsule-like negative surface charge

  • Only fimbriated (piliated) cells (formerly known as colony types T1 & T2) are virulent

  • Outer membrane proteins (formerly Proteins I, II, & III)

    • Por (porin protein) prevents phagolysosome fusion following phagocytosis and thereby promotes intracellular survival

    • Opa (opacity protein) mediates firm attachment to epithelial cells and subsequent invasion into cells

    • Rmp (reduction-modifiable protein) protects other surface antigens from bactericidal antibodies (Por protein, LOS)

  • Acquisition of iron mediated through Tbp 1 and Tbp 2 (transferrin-binding proteins), Lbp (lactoferrin binding protein) & Hbp (hemoglobin-binding protein)


Gonococcal spp.Virulence Factors (cont.)

  • Llipooligosaccharide (LOS) (Lipid A plus core polysaccharide but no O-somatic antigen polysaccharide side chain) has endotoxin activity

  • IgA1 protease

  • Acquisition in last two decades of two types of antibiotic resistance:

    • Plasmid-encoded beta-lactamase production

    • Chromosomally-mediated changes in cellular permeability inhibit entry of penicillins, tetracycline, erythromycin, aminoglycosides


Laboratory Characterization spp.

  • Small, gram-negative diplococci in presence of polymorphonuclear leukocytes (PMN’s) seen microscopically in purulenturethral discharge

  • Susceptible to drying and cooling, so immediate culture of specimen onto pre-warmed selective (e.g., modified Thayer-Martin, Martin-Lewis agars) and non-selective media (chocolate blood agar) with moist atmosphere containing 5% carbon dioxide

  • Some strains inhibited by vancomycin (in many selective agars) and toxic substances like fatty acids and trace metals in protein hydrolysates and agar found in nonselective media

  • Five morphologically distinct colony types (formerly T1 through T5) that can undergo phase transition are no longer considered to be a useful distinction


Prevention & Treatment spp.

  • Penicillin no longer drug of choice due to:

    • Continuing rise in the MIC

    • Plasmid-encoded beta-lactamase production

    • Chromosomally-mediated resistance

  • Uncomplicated infxn: ceftriaxone, cefixime or fluoroquinolone

  • Combined with doxycycline or azithromycin for dual infections with Chlamydia

  • Chemoprophylaxis of newborns against opthalmia neonatorum with 1% silver nitrate, 1% tetracycline, or 0.5% erythromycin eye ointments

  • Treatment of newborns with opthalmia neonatorum with ceftriaxone

  • Measures to limit epidemic include education, aggressive detection, and follow-up screening of sexual partners, use of condoms or spermicides with nonoxynol 9


Analytic Performance of Different Laboratory Detection Methods for Nesseria gonorrhoeae

NOTE: Importance ofSensitivity vs. Specificityfor any Diagnostic Test


See Handout on Sensitivity & Specificity of Diagnostic Tests Methods for Nesseria gonorrhoeae

(Next two slides)


Analytic Performance of a Diagnostic Test Methods for Nesseria gonorrhoeae


Analytic Performance of a Diagnostic Test Methods for Nesseria gonorrhoeae(cont.)

  • Sensitivity = Measure of True Positive Rate (TPR)

  • = No. of True Pos. = No. of True Pos. = 80 = 80%

  • No. of Actual Pos. No. of (True Pos. + False Neg.) 80+20 Sensitivity

    • In conditional probability terms, the probability of a positive test given an actual positive sample/patient.

  • Specificity = Measure of True Negative Rate (TNR)

  • = No. of True Neg. = No. of True Neg. = 75 = 75%

  • No. of Actual Neg. No. of (True Neg. + False Pos.) 75+25 Specificity

    • In conditional probability terms, the probability of a negative test given an actual negative sample/patient.


Neisseria meningitidis Methods for Nesseria gonorrhoeae

(meningococcus)


General Overview of Neisseria meningitidis Methods for Nesseria gonorrhoeae

  • Encapsulated small, gram-negative diplococci

  • Second most common cause (behind S. pneumoniae) of community-acquired meningitis in previously healthy adults; swift progression from good health to life-threatening disease

  • Pathogenicity:

    • Pili-mediated, receptor-specific colonization of nonciliated cells of nasopharynx

    • Antiphagocytic polysaccharide capsule allows systemic spread in absence of specific immunity

    • Toxic effects mediated by hyperproduction of lipooligosaccharide

  • Serogroups A, B, C, Y, W135 account for about 90% of all infections


Diseases Associated with Neisseria meningitidis Methods for Nesseria gonorrhoeae

  • Following dissemination of virulent organisms from the nasopharynx:

    • Meningitis

    • Septicemia (meningococcemia) with or without meningitis

    • Meningoencephalitis

    • Pneumonia

    • Arthritis

    • Urethritis


Neisseria meningitidis in Cerebrospinal Fluid Methods for Nesseria gonorrhoeae


Epidemiology of Meningococcal Disease Methods for Nesseria gonorrhoeae

  • Humans only natural hosts

  • Person-to-person transmission by aerosolization of respiratory tract secretions in crowded conditions

  • Close contact with infectious person (e.g., family members, day care centers, military barracks, prisons, and other institutional settings)

  • Highest incidence in children younger than 5 years and particularly those younger than 1 year of age as passive maternal antibody declines and as infants immune system matures

  • Commonly colonize nasopharynx of healthy individuals; highest oral and nasopharyngeal carriage rates in school-age children, young adults and lower socioeconomic groups


Age Distribution of Meningococcal Disease in USA Methods for Nesseria gonorrhoeae

Lacking maternal antibody


Pathogenesis of Meningococcal Disease Methods for Nesseria gonorrhoeae

  • Specific receptors (GD1 ganglioside) for bacterial fimbriae on nonciliated columnar epithelialcells in nasopharynx of host

  • Organisms are internalized into phagocytic vacuoles, avoid intracellular killing in absence of humoral immunity and complement system (patients with late complement deficiencies are particularly at risk)

  • Replicate intracellularly and migrate to subepithelial space where excess membrane fragments are released

  • Hyperproduction of endotoxin (lipid A of LOS) and blebbing into surrounding environment (e.g., subepithelial spaces, bloodstream) mediates most clinical manifestations including diffuse vascular damage (e.g., endothelial damage, vasculitis (inflammation of vessel walls), thrombosis (clotting), disseminated intravascular coagulation (DIC)


Skin Lesions of Meningococcemia Methods for Nesseria gonorrhoeae

NOTE:Petechiae have coalesced into hemorrhagic bullae.


Immunogenicity of Neisseria meningitidis Methods for Nesseria gonorrhoeae

  • Following colonization of the nasopharynx, protective humoral immunity develops against the same or closely related organisms of the same serogroup, but not against other serogroups

  • Bactericidal activity of the complement system is required for clearance of the organisms

  • Cross-reactive protective immunity acquired with colonization by closely related antigenic strains and with normal flora of other genera (e.g., E. coli K1); progressive disease can occur in absence of serogroup-specific immunity


Laboratory Characterization of Neisseria meningitidis Methods for Nesseria gonorrhoeae

  • Large numbers (e.g., >107cells/ml) of encapsulated, small, gram-negative diplococci (flattened along adjoining side) and polymorphonuclear leukocytes (PMN’s) can be seen microscopically in cerebrospinal fluid (CSF)

  • Transparent, non-pigmented nonhemolytic colonies on chocolate blood agar with enhanced growth in moist atmosphere with 5% CO2

  • Oxidase-positive

  • Acid production from glucose and maltose but not from other sugars


Prevention and Treatment of Meningococcal Disease Methods for Nesseria gonorrhoeae

  • Penicillin is drug of choice for treatment in adjunct with supportive therapy for meningeal symptoms

    • Increasing MIC mediated by genetic alteration of target penicillin binding proteins is being monitored)

    • Chloramphenicol or cephalosporins as alternatives

  • Chemoprophylaxis of close contacts with rifampin or sulfadiazine (if susceptible)

  • Polyvalent vaccine containing serogroups A, C, Y, and W135 is effective in people older than 2 years of age for immunoprophylaxis as an adjunct to chemoprophylaxis

    • Serogroup B is only weakly immunogenic and protection must be acquired naturally from exposure to cross-reacting antigens


REVIEW Methods for Nesseria gonorrhoeae

of

Neisseria


General Characteristics of Neisseria spp. Methods for Nesseria gonorrhoeae

  • Aerobic

  • Gram-negative cocci often arranged in pairs (diplococci) with adjacent sides flattened (like coffe beans)

  • Oxidase positive

  • Most catalase positive

  • Nonmotile

  • Acid from oxidation of carbohydrates, not from fermentation

REVIEW


Neisseria Associated Diseases Methods for Nesseria gonorrhoeae

(ophthalmia neonatorum)

REVIEW


Review of Methods for Nesseria gonorrhoeaeNeisseria gonorrhoeae


General Overview of Neisseria gonorrhoeae Methods for Nesseria gonorrhoeae

  • Readily transmitted by sexual contact

  • Gram-negative diplococci flattened along the adjoining side

  • Fastidious, capnophilic and susceptible to cool temperatures, drying and fatty acids

    • Requires complex media pre-warmed to 35-37C

    • Soluble starch added to neutralize fatty acid toxicity

    • Grow best in moist atmosphere supplemented with CO2

  • Produce acid from glucose, but not from other sugars

REVIEW


Summary of Neisseria gonorrhoeae Methods for Nesseria gonorrhoeae

REVIEW


Summary of Neisseria gonorrhoeae Methods for Nesseria gonorrhoeae(cont.)

REVIEW


Epidemiology of Gonorrhea Methods for Nesseria gonorrhoeae

  • Seriously underreported sexually-transmitted disease

    • 350,000 reported cases in 1998

  • Found only in humans with strikingly different epidemiological presentations for females and males

  • Asymptomatic carriage is major reservoir

  • Transmission primarily by sexual contact

  • Lack of protective immunity and therefore reinfection, partly due to antigenic diversity of strains

  • Higher risk of disseminated disease in patients with late complement deficiencies

REVIEW


REVIEW Methods for Nesseria gonorrhoeae


Pathogenesis of Neisseria gonorrhoeae Methods for Nesseria gonorrhoeae

  • Fimbriated cells attach to intact mucus membrane epithelium

  • Capacity to invade intact mucus membranes or skin with abrasions

    • Adherence to mucosal epithelium

    • Penetration into and multiplication before passing through mucosal epithelial cells

    • Establish infection in the sub-epithelial layer

  • Most common sites of inoculation:

    • Cervix (cervicitis) or vagina in the female

    • Urethra (urethritis) or penis in the male

REVIEW


Virulence Factors Associated with Neisseria gonorrhoeae Methods for Nesseria gonorrhoeae

REVIEW


See Handout on Sensitivity & Specificity of Diagnostic Tests Methods for Nesseria gonorrhoeae

(Next two slides)


Analytic Performance of a Diagnostic Test Methods for Nesseria gonorrhoeae

REVIEW


Analytic Performance of a Diagnostic Test Methods for Nesseria gonorrhoeae(cont.)

  • Sensitivity = Measure of True Positive Rate (TPR)

  • = No. of True Pos. = No. of True Pos. = 80 = 80%

  • No. of Actual Pos. No. of (True Pos. + False Neg.) 80+20 Sensitivity

    • In conditional probability terms, the probability of a positive test given an actual positive sample/patient.

  • Specificity = Measure of True Negative Rate (TNR)

  • = No. of True Neg. = No. of True Neg. = 75 = 75%

  • No. of Actual Neg. No. of (True Neg. + False Pos.) 75+25 Specificity

    • In conditional probability terms, the probability of a negative test given an actual negative sample/patient.

REVIEW


Review of Methods for Nesseria gonorrhoeaeNeisseria meningitidis


General Overview of Neisseria meningitidis Methods for Nesseria gonorrhoeae

  • Encapsulated small, gram-negative diplococci

  • Second most common cause (behind S. pneumoniae) of community-acquired meningitis in previously healthy adults; swift progression from good health to life-threatening disease

  • Pathogenicity:

    • Pili-mediated, receptor-specific colonization of nonciliated cells of nasopharynx

    • Antiphagocytic polysaccharide capsule allows systemic spread in absence of specific immunity

    • Toxic effects mediated by hyperproduction of lipooligosaccharide

  • Serogroups A, B, C, Y, W135 account for about 90% of all infections

REVIEW


Summary of Neisseria meningitidis Methods for Nesseria gonorrhoeae

REVIEW


Summary of Neisseria meningitidis Methods for Nesseria gonorrhoeae(cont.)

REVIEW


Diseases Associated with Neisseria meningitidis Methods for Nesseria gonorrhoeae

  • Following dissemination of virulent organisms from the nasopharynx:

    • Meningitis

    • Septicemia (meningococcemia) with or without meningitis

    • Meningoencephalitis

    • Pneumonia

    • Arthritis

    • Urethritis

REVIEW


Epidemiology of Meningococcal Disease Methods for Nesseria gonorrhoeae

  • Humans only natural hosts

  • Person-to-person transmission by aerosolization of respiratory tract secretions in crowded conditions

  • Close contact with infectious person (e.g., family members, day care centers, military barracks, prisons, and other institutional settings)

  • Highest incidence in children younger than 5 years and particularly those younger than 1 year of age as passive maternal antibody declines and as infants immune system matures

  • Commonly colonize nasopharynx of healthy individuals; highest oral and nasopharyngeal carriage rates in school-age children, young adults and lower socioeconomic groups

REVIEW


Age Distribution of Meningococcal Disease in USA Methods for Nesseria gonorrhoeae

REVIEW


Pathogenesis of Meningococcal Disease Methods for Nesseria gonorrhoeae

  • Specific receptors (GD1 ganglioside) for bacterial fimbriae on nonciliated columnar epithelialcells in nasopharynx of host

  • Organisms are internalized into phagocytic vacuoles, avoid intracellular killing in absence of humoral immunity and complement system (patients with late complement deficiencies are particularly at risk)

  • Replicate intracellularly and migrate to subepithelial space where excess membrane fragments are released

  • Hyperproduction of endotoxin (lipid A of LOS) and blebbing into surrounding environment (e.g., subepithelial spaces, bloodstream) mediates most clinical manifestations including diffuse vascular damage (e.g., endothelial damage, vasculitis (inflammation of vessel walls), thrombosis (clotting), disseminated intravascular coagulation (DIC)

REVIEW


Immunogenicity of Neisseria meningitidis Methods for Nesseria gonorrhoeae

  • Following colonization of the nasopharynx, protective humoral immunity develops against the same or closely related organisms of the same serogroup, but not against other serogroups

  • Bactericidal activity of the complement system is required for clearance of the organisms

  • Cross-reactive protective immunity acquired with colonization by closely related antigenic strains and with normal flora of other genera (e.g., E. coli K1); progressive disease can occur in absence of serogroup-specific immunity

REVIEW


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